Ascocerida

The Ascocerida are comparatively small, bizarre Orthoceratoids known only from Ordovician and Silurian sediments in Europe and North America, uniquely characterized by a deciduous conch consisting of a longer juvenile portion and an inflated short adult portion that separate sometime in maturity.

==Morphology== The juvenile portion of an ascocerid consists typically of a narrow, circular cyrtocone that underwent periodic truncation. Cumulative length, including broken off segments, may have reached about in the largest individuals. The siphuncle is located halfway between the shell axis and the venter, is thin walled and tubular with short, orthochoanitic septal necks and segments that are only slightly inflated. The juvenile portion is known as the deciduous conch, as it is shed in a similar manner to deciduous trees losing their leaves.